Frozen confection and process of making

ABSTRACT

The process involves feeding a base aerated frozen confection having an overrun of from 20-150% from a freezer to a static mixer, feeding a viscous flavorant or other ingredient having a free oil level of at least 10% to the static mixer to combine with the base frozen confection, and mixing them in the static mixer to obtain a frozen confection including the viscous flavorant or other ingredient which is homogeneous to the eye and taste and which preferably has fewer crystalline fat structures per air bubble, which means greater stability of the air bubbles. The invention is also reflected in reduced standard deviation in product fill weight and an improved distribution of air bubbles. The invention also is directed to the frozen aerated confection.

BACKGROUND OF THE INVENTION

Ice cream is an indulgence food much favored by consumers. Yet, icecream manufacturers are always looking for ways to make their productseven more appealing.

A well known route for improving aerated frozen confections such as icecream involves incorporating viscous, free oil-containing flavoringsinto the product. In some cases, it is desired that the flavoring beincorporated in a way such that the frozen confection is homogeneous tothe eye and the taste. One such flavoring desired by consumers is peanutbutter.

Unfortunately, we have found that it is difficult to incorporatehomogeneously large amounts of viscous, free oil-containing flavoringssuch as peanut butter into aerated frozen confections after they havebeen homogenized without risking poor texture, variable overrun and ahigh degree of weight variation. Indeed, it is known that too muchliquid oil present during dynamic freezing leads to a poor airstructure. This makes it difficult to produce high weight levels ofhomogeneous peanut butter frozen confection. While frozen confectionswith lower levels of peanut butter can be enjoyed, in order to furnishconsumers with high quality products, it is desirable to be able toinclude higher levels of peanut butter in such products.

There is ample patent and other literature concerning mixing ofingredients.

Kirk-Othmer, Encyclopedia of Chemical Technology, 4^(th) edition, Volume16, John Wiley & Sons, 1995, pages 874-875 indicates that static mixersare used in food manufacture, e.g., oils, juices, beverages, milk,sauces, emulsifications and heat transfers.

WO 2005/031226 is directed to a method for combining cryogenicallyfrozen food with conventional ice cream. The cryogenically frozen foodsmay include cranberries, pieces of other fruit, pieces of chocolate,various types of candies, pieces of cookie dough, or any of thesecovered in chocolate. In one embodiment, food particles are combinedwith a semi-frozen soft ice cream from a barrel freezer by a combiningmechanism which forces the combination through a static mixer.

GB 1,386,955 discloses turbulence-promoting devices useful as mixers.They comprise a substantially circular section tube having a pluralityof turbulence-promoting elements in engagement with the wall of thetube. They are described as static. The device is said to beparticularly useful for mixing shear-sensitive materials such as yogurtwith whole or comminuted fruit. The controlled mixing of ice cream toproduce a ripple effect is also mentioned as an application.

Ulrich et al. US Patent Application Publication No. 2006/0102016 isdirected to an apparatus for combining particulate and traditional icecream. A pre-mixing device allows several compositions, not all of whichmust be liquid, such as powdered flavorings or other additives of a sizesmall enough not to cause clogging in the feed assembly, to be mixed fordelivery to the feed tray. Particulate ice cream beads are combined withsemi-frozen soft ice cream from a barrel freezer by a stuffing pump,which forces the combination through a static mixer where it is blendedand then output to a container for consumption.

GB 914,331 discloses a continuous ice cream freezer which receivesliquid mix from one end, thoroughly mixes it with air using a helicalmixer, and discharges it in the form of ice cream. The helical mixer ishoused for rotation.

Vaghela et al. U.S. Pat. No. 5,968,582 discloses a process for producinga molded aerated frozen bar. The process includes preparing a mix ofingredients, whipping the mix to obtain an aerated mix, molding theaerated mix, and freezing the molded aerated mix.

It is known that free oil in an ice cream can interfere with air bubblesand result in poor texture. Marshall et al. “Ice cream,” 6^(th) edition,Springer, (2003) p. 69 discloses that if too much oil is present duringdynamic freezing, it spreads at the air surface leading to collapse ofair bubbles and undesirable texture.

SUMMARY OF THE INVENTION

The present invention is directed to a process of preparing a frozenconfection containing a viscous, free oil-containing flavoring (or otherviscous free oil-containing ingredient) and to a frozen confection whichmay be prepared by the process. By mixing in the viscousflavoring/ingredient using a static mixer after the base frozenconfection has been subjected to treatment in the freezer, toward theend of the manufacturing process, it is possible to incorporate higheramounts of the viscous flavoring/ingredient into the product. Moreover,although the presence of viscous, free oil-containingflavorings/ingredients during conventional manufacturing can impair thequality of frozen confections, products made in accordance with theinvention do not suffer from the poor texture, variable overrun and highdegree of weight variation to which products made using conventionalprocesses are subject.

The improved process of the invention is reflected in a reduced standarddeviation for product. With the process of the invention, the standarddeviation for product weight for a frozen confection over 1 hour ofproduction with a sample size of at least 4 samples incorporating from5-18 wt % of a viscous flavoring/ingredient having a free oil level ofat least 10 wt % is advantageously less than 3.5%, especially less than3%.

Another advantage to adding peanut butter or other viscous, freeoil-containing flavorings after the confection has been subjected tofreezing and aeration in the freezer is that since peanut butter is anallergen, addition later in the process minimizes the exposure ofequipment to it as much as possible. For instance, adding peanut butterlater in the process avoids the need to clean the freezer for peanutallergen specifically when switching flavors.

The frozen confection of the invention enjoys a more favorabledistribution of air bubbles as reflected in a PDF (probability densityfunction) for the largest bubble of at least 0.013, preferably at least0.015, most preferably at least 0.018.

The frozen confection of the invention also has fewer crystalline fatstructures per air bubble, which means greater stability of the airbubbles. Preferably, for a frozen aerated confection according to theinvention flavored with a viscous free oil-containing flavorant oringredient comprising at least 5 wt % viscous flavoring/ingredient andat least 80 wt % of a base frozen confection, there are fewer than 0.01crystalline structures per square micron of air bubble. More preferablythere are fewer than 0.009 structures per square micron of air bubbleand most preferably fewer than 0.0075 structures per square micron ofair bubble. The frozen aerated confection more preferably includes from6-20 wt % of the viscous oil-containing flavoring/ingredient.

In accordance with a preferred aspect of the invention, the frozenconfection of the invention is homogeneous to eye and taste,notwithstanding the incorporation of the viscous, free oil-containingflavorant or other ingredient. The invention is also reflected in aconsistent line speed comparable for the same product without viscousflavorings.

The process of the invention is particularly advantageous for freeoil-containing, viscous flavorings such as peanut butter, hazelnutbutter, almond butter and other nut butters, and for coconut pastes.Viscous, free oil-containing flavorings or other ingredients containingat least 10 wt % free oil are particularly preferred. Typically, thefree oil will constitute up to 60 wt % of the flavoring/ingredient. Theflavorings/ingredients used in the invention are non-particulate and maybe in the form of a paste or a butter.

Preferably, then, the invention involves feeding a base aerated frozenconfection having an overrun of from 20-150% from a freezer to a staticmixer, feeding a viscous flavorant or other ingredient having a free oillevel of at least 10% to the static mixer to combine with the basefrozen confection, and mixing them in the static mixer to obtain afrozen confection including the viscous flavorant or other ingredientwhich is homogeneous to the eye and taste and which preferably has fewercrystalline fat structures per air bubble, which means greater stabilityof the air bubbles. Preferably for a frozen aerated confection accordingto the invention flavored with a viscous free oil-containing flavorantor ingredient comprising at least 5 wt % viscous flavoring/ingredientand at least 80 wt % of a base frozen confection, there are fewer than0.01 crystalline structures per square micron of air bubble, morepreferably fewer than 0.009 structures per square micron of air bubbleand most preferably fewer than 0.0075 structures per square micron ofair bubble. The advantage of the compositions of the invention in thisrespect increases with increasing levels of viscous ingredient such asfor 10 wt % and greater, viscous ingredient, and 15 wt % and greaterviscous ingredient. Preferably the standard deviation for tub weight ofthe frozen confections is less than 3.5%. The level of viscous flavorantor other ingredient is preferably from 5-18 wt %, preferably from 8-16wt %.

For a more complete of the above and other features and advantages ofthe invention, reference should be made to the following description ofthe preferred.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of a first part of the ice creamproduction process, showing conventional steps other than feeding to thestatic mixer.

FIG. 2 is a schematic diagram of a second part of the ice creamproduction process.

FIG. 3 shows scanning electron microscope (SEM) images of ice creammicrostructure for a) on the left, an ice cream made using the Staticmixer process of the invention at 100× magnification where the ice creamcontained 12% peanut butter and b) on the right, ice cream made usingthe conventional process using a univat without a Static mixer at 100×magnification where the ice cream contained 12% peanut butter.

FIG. 4 shows SEM images of ice cream microstructure for a) on the left,an ice cream made using the Static mixer process at 100× magnificationwhere the ice cream contained 16% peanut butter and b) on the right, icecream made using the conventional process using a univat without aStatic mixer at 100× magnification where the ice cream contained 16%peanut butter.

FIG. 5 shows SEM images of ice cream microstructure for a) on the left,an ice cream made using the Static mixer process at 1000× magnificationwhere the ice cream contained 12% peanut butter and b) on the right, icecream made using the conventional process using a univat without aStatic mixer at 1000× magnification where the ice cream contained 12%peanut butter.

FIG. 6 shows SEM images of ice cream microstructure for a) on the left,an ice cream made using the Static mixer process at 4000× magnificationwhere the ice cream contained 12% peanut butter and b) on the right, icecream made using the conventional process using a univat without aStatic mixer at 4000× magnification where the ice cream contained 12%peanut butter.

FIG. 7 shows scanning electron microscope images marked to show thediameter of the air bubbles.

FIG. 8 is a histogram showing the standard deviation and maximum bubblesize of samples according to the invention and conventional samples.

FIG. 9 is a histogram of the PDF values of the largest bubble at eachpercentage evaluated for samples according to the invention and forsamples made according to a conventional process.

FIG. 10 is a histogram showing standard deviation of product weight forproducts made in accordance with the invention and for conventionalproducts.

FIG. 11 is a graph of the crystalline structures per square um as afunction of PB Percentage.

FIG. 12a is a graph of the crystalline structures per square um as afunction of hazelnut butter and of peanut butter percentages.

FIG. 12b is a graph of crystals/spikes per square um as a function ofhazelnut butter percentage and of peanut butter percentages.

FIG. 13 shows SEM images taken at 1000× magnification of ice creammicrostructure for a) on the top, an ice cream made using the Staticmixer process of the invention where the ice cream contains 5% hazelnutbutter and b) on the bottom, ice cream made using the conventionalprocess using a univat without a Static mixer where the ice creamcontains 5% hazelnut butter.

FIG. 14 shows SEM images of ice cream microstructure taken at 1000×magnification for a) on the top, an ice cream made using the Staticmixer process of the invention where the ice cream contains 12% hazelnutbutter and b) on the bottom, ice cream made using the conventionalprocess using a univat without a Static mixer where the ice creamcontains 12% hazelnut butter.

FIG. 15 shows SEM images of ice cream microstructure taken at 1000×magnification for a) on the top, an ice cream made using the Staticmixer process where the ice cream contains 20% hazelnut butter and b) onthe bottom, ice cream made using the conventional process using a univatwithout a Static mixer where the ice cream contains 20% hazelnut butter.

DETAILED DESCRIPTION OF THE INVENTION

In contrast to more typical levels for peanut butter and other viscousflavorings incorporated into frozen confections made by conventionalprocesses of 0.5-5 wt %, it is believed that the present process willpermit higher levels of viscous, free oil-containing, flavorant or otheringredient of from 5-20 wt %, especially from 6-18 wt %, preferably from8-15 wt %, most preferably from 11-15 wt %, while still providing aconfection with good texture, consistent overrun and low degrees ofweight variation.

While not wishing to be bound by theory, it is believed that the freeoil in viscous flavorings such as peanut butter adversely impacts theaeration of the mix, resulting in the poor texture, variable overrun andhigh degree of weight variation in production. By adding the viscous,free oil-containing flavoring after the freezing and aeration step, theinteraction between the free oil and the aeration is avoided. Similaradverse interactions between oil and air bubbles are believed not tooccur with the oil present as part of the frozen confection inconventional steps prior to combination with the flavorant/ingredientsince the size of such bubbles are reduced during homogenization.

Viscous flavorings or other ingredients are non-solids. They arepreferably soft enough (generally semi-solid or liquid) to be pumped tothe static mixer and, after mixing in the static mixer, form a frozenconfection which is homogeneous to taste and to the eye. One of ordinaryskill can ascertain whether the flavorant/ingredient is sufficientlynon-solid. Examples of viscous flavorings include nut pastes such aspeanut butter, almond butter, etc.

The viscous flavoring is preferably present in the frozen confection atlevels of from 2.5 to 20 wt %, especially from 5-16 wt %. The basefrozen confection is preferably present at from 97.5 to 70 wt %,especially from 80 to 96 wt %.

A preferred viscous flavoring is peanut butter base having 10-60 wt %free oil.

One of ordinary skill will be able to determine the level of free oil ina flavoring/ingredient, e.g., by checking how much oil settles out ofthe flavoring/ingredient in 5 days.

Static mixers are motionless mixers which derive the fluid motion orenergy dissipation needed for mixing from the flowing fluid itself. Theycomprise repeated structures referred to as mixing elements attachedinside a pipe. The mixing elements divide and recombine fluids whichpass therethrough. A static mixer useful in the present invention, ModelNo. GXM-3.834 inch, is available from StaMixCo of Brooklyn, N.Y. Anumber of static mixing elements, such as 6, may be used in series. Oneof ordinary skill can ascertain the number of static mixing elementsneeded for a particular application. A center point sparger may belocated just prior to the first static mixing element.

The base frozen confection (prior to combining with the viscousflavorant/ingredient) is preferably aerated, i.e., it has an overrun ofmore than 20 percent, preferably more than 30 percent, more preferablymore than 50 percent. Preferably the base frozen confection has anoverrun of less than 200 percent, more preferably less than 150 percent,most preferably less than 120 percent. Overrun is defined by theequation below and is measured at atmospheric pressure:

Overrun %=((density of mix−density of frozen confection)/density offrozen confection)×100

The frozen confection is a frozen product, such as ice cream, sherbet,water ice and the like. “Frozen,” as used herein, denotes that theproduct is solidified under freezing conditions to a hardpack orpumpable consistency. The ice content of the frozen confection should bemore than 15% but less than 45%. The frozen confection flavored with theviscous, free oil-containing flavorant or other ingredient may becombined with other ingredients such as wafers in an ice cream sandwichor an appropriate sauce in a sundae. The frozen confection is preferablya water-continuous emulsion.

Generally the product of the invention will include a dairy source, suchas whole milk, skim milk, condensed milk, evaporated milk, cream,butter, butterfat, whey, milk solids non-fat, etc. The dairy source willgenerally contribute dairy fat and/or non-fat milk solids such aslactose and milk proteins, e.g. whey proteins and caseins. A dairyprotein powder, such as whey protein, may be used as a protein source.Lactose will generally be present in the base frozen confections used inthe invention within the range of from 0 to 8 wt percent, especiallyfrom 0.5 to 7 percent, more preferably from 3 to 8 wt percent (excludingthe viscous flavoring—that is, the ice cream or the like to which theviscous flavoring is added). Dairy proteins will generally be present inthe base frozen confections of the invention at from 1 to 5 wt percent,especially from 1 to 3 wt percent (excluding viscous flavoring). Otherproteins may be present at from 0 to 3 wt percent.

While butter fat from cream and other dairy sources is preferred in thebase frozen confection, alternative fat sources, such as vegetable fat,may be used in some embodiments of the invention. For example, fats maybe taken from the group which includes cocoa butter, illipe, shea, palm,palm kernal, sal, soybean, cottonseed, coconut, rapeseed, canola, andsunflower oils and mixture thereof.

The level of triglyceride fat in the base frozen confection product,excluding the viscous flavorant, indeed preferably the total level ofdigestable lipid in the base frozen confection product, is preferablyfrom 2 weight percent to 20 wt %, more preferably, from 3 wt % to 15 wt%.

If desired, the product may include an emulsifying agent. Typicalemulsifying agents may be phospholipids and proteins, such as dairy orsoy proteins, or esters of long chain fatty acids and a polyhydricalcohol. Fatty acid esters of glycerol, polyglycerol esters of fattyacids, sorbitan esters of fatty acids and polyoxyethylene andpolyoxypropylene esters of fatty acids may be used but organolepticproperties, or course, must be considered. Mono- and di-glycerides mayalso be used but may also be omitted. Indeed, emulsifiers other thanproteins and phospholipids may be omitted. If present, non-proteinemulsifiers are used in amounts of about 0.03 percent to 0.5 percent,preferably 0.1 percent to 0.3 percent by weight of the base frozenconfection, i.e. excluding the frozen confection to which the viscousflavoring is later added.

Gum stabilizers are particularly effective in controlling viscosity,providing mouth feel and improving whipping (aerating) properties; toprovide a protective colloid to stabilize proteins to heat processing;to modify the surface chemistry of fat surfaces to minimize creaming; toprovide acid stability to protein systems and; to increase freeze-thawstability. Gums can be classified as neutral and acidic, straight- andbranched-chain, gelling and non-gelling. The principal gums that may beused are Karaya gums, locust bean gum, carageenan, xanthan, guar,alginate and carboxymethyl cellulose.

Gums are generally used in concentrations of 0.02-0.5 weight percent ofthe base frozen confection composition. Because of differingfunctionalities, combinations of certain gums may provide a betterproduct than a single gum. For instance, for some types of frozenconfections karaya gum is ideally used together with polydextrose.

The stabilizer may be microcrystalline cellulose as described in U.S.Pat. No. 5,209,942, e.g., Avicel 581, which is activated or “peptized.”A combination of microcrystalline cellulose and sodium carboxymethylcellulose (CMC) may give good results.

Microcrystalline cellulose has been listed in the Fourth Supplement tothe Food Chemicals Codex, First Edition, by the National Academy ofSciences-National research Council as: Cellulose, Microcrystalline(cellulose gel). Cellulose gel in combination with cellulose gum isespecially preferred.

Another component may comprise one or any combination ofcarboxymethylcellulose (in addition to that with which themicrocrystalline cellulose may be coated), xanthan gum, starch andalginate.

If desired, gelatin, e.g., 225 bloom, may be included in the base frozenconfection compositions at levels of say 0.1-1 wt percent, especiallyfrom 0.1-0.3 wt percent. Certain salts such as phosphates and chloridesmay be employed to alter the buffering capacity of the system and toimprove the water binding capacity of proteins and improve solubilityand flavor. Sodium chloride and sodium monophosphate at very low levelsare preferred but calcium phosphate and particularly monocalciumphosphate may also be employed. Sodium chloride is preferred at levelsof 0.05 percent to 0.3 percent of the base frozen confection; and sodiummonophosphate is preferred at levels of 0.01 percent to 0.1 percent ofthe base frozen confection.

Generally the compositions of the invention will be naturally sweetened.Natural sources of sweetness include sucrose (liquid or solids),glucose, fructose, and corn syrup (liquid or solids). Other sweetenersinclude lactose, maltose, and galactose. Levels of sugars and sugarsources preferably result in sugar solids levels of up to 28 wt percentin the base frozen confection, preferably from 5 to 24 wt percent,especially from 10 to 24 wt percent.

If it is desired to use artificial sweeteners, any of the artificialsweeteners well known in the art may be used, such as aspartame,saccharine, Alitame (obtainable from Pfizer), acesulfame K (obtainablefrom Hoechst), cyclamates, neotame, sucralose and the like, and mixturesthereof. The sweeteners are used in varying amounts of about 0.005percent to 1 percent of the base frozen confection, preferably 0.007percent to 0.73 percent depending on the sweetener, for example.Aspartame may be used at a level of 0.01 percent to 0.15 percent of thebase frozen confection, preferably at a level of 0.01 percent to 0.05percent. Acesulfame K is preferred at a level of 0.01 percent to 0.15percent of the base frozen confection.

Natural low- or non-caloric sweeteners such as stevia may be used atlevels of from 0.01 to 0.15, especially 0.01 to 0.05 of the base frozenconfection.

If desired, the product may include polydextrose. Polydextrose functionsboth as a bulking agent and as a fiber source and is preferably includedat from 1 to 10 wt percent, especially from 3 to 6 wt percent of thebase frozen confection.

Polydextrose may be obtained under the brand name Litesse from DaniscoSweeteners. Among other fiber sources which may be included in thecompositions of the invention are fructose oligosaccharides such asinulin. Additional bulking agents which may be used includemaltodextrin, sugar alcohols, corn syrup solids, sugars or starches.Total bulking agent levels in the base frozen confections of theinvention will may be from about 5 percent to 20 percent, preferably 13percent to 16 percent.

If desired, sugar alcohols such as glycerol, sorbitol, lactatol,maltitol, manitol, etc. may be used to control ice formation. Ifpresent, sugar alcohols may be used in an amount of about 1 percent to 8percent, preferably 2.5 percent to 8.0 percent of the base frozenconfection. However, the present invention also contemplatesformulations in which glycerol is excluded.

In addition to the viscous, free oil-containing, flavoring, otherflavorings are preferably added to the product but preferably in amountsthat will impart a mild, pleasant flavor. The flavoring may be any ofthe commercial flavors employed in ice cream, such as varying types ofcocoa, pure vanilla or artificial flavor, such as vanillin, ethylvanillin, chocolate, extracts, spices and the like. It will further beappreciated that many flavor variations may be obtained by combinationsof the basic flavors. The confection compositions are flavored to tasteas mentioned above. Suitable flavorants may also include seasoning, suchas salt, and imitation fruit or chocolate flavors either singly or inany suitable combination.

Malt powder can be used, e.g., to impart flavor, preferably at levels offrom 0.01 to 3.0 wt percent of the base frozen confection, especiallyfrom 0.05 to 1 percent.

Preservatives such as potassium sorbate may be used as desired.

Adjuncts such as wafers, variegates (in addition to the viscous, freeoil-containing flavorings) and sauces/coatings may be included asdesired. In the case of sauces, coatings, they are typically present atfrom 5 to 30 weight percent of the viscous flavorant/ingredientcontaining frozen confection of the invention (including the weight ofthe sauce/coating.)

Water/moisture/ice will generally constitute the balance of the basefrozen confection at, e.g., from 40-90 wt %, especially from 50-75 wt %.

Apart from the addition of the viscous flavorant/ingredient, processesused for the manufacture of the product are similar to those used forconventional frozen confections. Typical process steps include:ingredient blending, pumping, pasteurization, homogenization, cooking,aeration, freezing and packaging. In accordance with the invention,after freezing and before packaging, the frozen confection is combinedwith the viscous, free oil-containing flavorant/ingredient in the staticmixer to form the frozen confection of the invention.

Products can be manufactured by batch or by continuous processes,preferably continuous. Ingredients may be either liquid or dry, or acombination of both. Liquid ingredients can be blended by the use ofpositive metering pumps to a mixing tank or by in-line blending. Dryingredients must be hydrated during the blending operations. This ismost commonly accomplished by the use of turbine mixers in processingvats or by incorporating the dry material through a high speed,centrifugal pump. The blending temperature depends upon the nature ofthe ingredients, but it must be above the melting point of any fat andsufficient to fully hydrate any gums used as stabilizers and anyproteins.

Pasteurization is generally carried out in high temperature short time(HTST) units, in which the homogenizer is integrated into thepasteurization system. Protein and any microcrystalline cellulose areadvisedly fully hydrated before adding other components which mightinterfere with the hydration.

SEM Analysis

All SEM analyses described below were performed using a JSM 6310Fscanning electron microscope fitted with an Oxford Instruments ITC4controlled cold stage. The samples were prepared using the HexlandCP2000 preparation equipment. A sample of size 5×5×3 mm was taken fromthe centre of a 500 ml block of ice cream. This sample was mounted ontoan aluminum stub and plunged into nitrogen slush. The sample wasfractured and the surface coated with Au/Pd at −115 degC and 2×10⁻¹mBar. The sample was examined under microscope conditions of −160 degCand 1×10⁻⁸ Pa.

Quantification of Gas Structure from SEM Images

The ImageJ 1.48v (National Institute of Health, USA) software run on aJava 1.6.0_20 platform was used to quantify the gas structure in icecream by measuring the gas cell size distribution from SEM images.

All sizes were measured from SEM micrographs at ×100 magnification usingthe ImageJ image analysis software. This magnification was such thatthere were approximately 300 gas cells per image. The scale of the imagewas set by manually measuring the scale on the image and calculating thesize per pixel. The program was used semi-automatically by drawing thediameters, which the program would then mark and measure. The diameterof each bubble was marked, so that the area of that bubble wasaccurately described by that length. The distribution was analyzed usingthe maximum diameter parameter. All gas cells present on a SEMmicrograph were counted and up to four SEM images were used. In generalat least 1000 gas cells were counted. The average size was determined asthe number average (d(1,0)) of the individual cell sizes.

Quantification of Fat Crystal Structures from SEM Images

The ImageJ 1.48v (National Institute of Health, USA) software run on aJava 1.6.0_20 platform was used to quantify the fat crystal structuresin ice cream.

All sizes were measured from SEM micrographs at λ1000 magnificationusing the ImageJ image analysis software. This magnification was suchthat there were approximately 5 gas cells per image. The scale of theimage was set by manually measuring the scale on the image andcalculating the size per pixel. The program was used semi-automaticallyby using the free form tool to circle each relevant air structure. Theprogram was used to mark the air structure and calculate the total areaof that structure. All gas cells present on a SEM micrograph werecounted and up to four SEM images were used. After marking all of theair structures on a single image, each of the crystalline fat structureswere marked using the point selection tool. The results were thenanalyzed to find the number of fat structures over the entire markedarea.

Unless stated otherwise or required by context, the terms “fat” can beeither liquid or solid at room temperature and “oil” is liquid at roomtemperature. In addition, unless otherwise stated or required bycontext, percentages are by weight. Unless otherwise stated or requiredby context weight percentages for the base frozen confection exclude theviscous flavorant/ingredient. Unless otherwise indicated or required bycontext, weight percentages for the viscous flavored frozen confectioninclude the viscous flavorant/ingredient but exclude any coatings. Asused herein the term viscous ingredient includes, but is not limited to,viscous flavorant. Homogeneous means that the frozen confection appearsto the eye and to the taste to be a single material and that thepresence of more than one material is barely, if at all, discernable.

Example

The purpose of this experiment is to test and compare two differentmethods of adding to ice cream a peanut butter base at various levels ofpeanut butter. The goal of the experiment is to compare the results. Twomethods of adding peanut butter base were tested during the experiment:(A) mixing with a static mixer according to the invention and (B) addingpeanut butter base to a univat mixing tank (post-pasteurization). Thepeanut butter base was added at various levels between 2.5 and 20 weightpercent, particularly focusing on 5, 12 and 16%.

Method (A) is according to the process of the invention whereas Method(B) reflects a more conventional method wherein peanut butter base hasbeen added to the univat without use of a static mixer.

FIG. 1 outlines the ice cream production process and the methods beinginvestigated. FIG. 2 shows a mixing flow diagram for a static mixer inthe process according to the invention. The followingequipment/parameters were used:

The univat is a 25 gallon continuously stirred vessel. The vessel isagitated using a Lightnin (brand name) mixer, with ¼ HP.

A center point spa rger was located just prior to the first staticmixing element.

Pasteurization Temperature at end of hold tube: 182.0-185.1 F

Pasteurization Flow rate: 3.6-4.0 L/min

Homogenization Pressures: 2100 psi first stage, 600 psi second stage

Overrun: 100%

Ice Cream Extrusion Temperature: 23.7-24.5 F

Freezer flow rate: 120 L/hr

The formula for the frozen confection (ice cream) was as follows:

Ingredient wt % BUTTER FAT 8. SKIMMED MILK POWDER 10. SUCROSE 13. CREAM4. FLAVORING 0.01 CARRAGENAN 0.02 LOCUST BEAN GUM 0.14 WATER 64.632 Mono& diglycerides 0.2 of fatty acids

Procedure:

To establish the method that produces the best results, the only changesto the process should be the method of peanut butter base addition andthe amount added. Unfortunately, it is impossible to perfectly replicatethe process due to uncontrolled factors. To fully understand the resultsof the experiment, it is important to consider each of the factors thatmight contribute to differences between the samples.

Category:

-   -   Inputs—The variables that are changing in the process        -   Method (Static, Univat)        -   Amount of Peanut Butter    -   Controlled Factors—Factors that are held constant in throughout        the tests        -   Pasteurization Technique: Always HTST        -   Homogenization Pressure        -   Overrun        -   Temperature (Compressor Work Load)        -   Batch Formula        -   Freezer: Hoyer ECT-5        -   Flow Rate    -   Uncontrolled Factors—Factors that cannot be controlled        -   Date of Mixing and Freezing        -   New Batch for each experimental sample        -   Ambient Temperature        -   Batch and Consistency of PB (Mixed by hand)    -   Outputs—Results from all contributing factors        -   Statistical Analysis of Microstructure of Ice Cream        -   Cup Weight of Product—Plant Trials

After looking at each category in depth, it was determined that theuncontrolled factors should not produce a significant change in thefinished product. Therefore, the experiment provides a reasonableassessment of product microstructure associated with each method. Eachvariant was sampled and microstructure was examined in depth. Theresults from these tests can be found in the following section.

Results and Discussion:

In its simplest form, ice cream is a frozen and aerated mixture ofwater, cream and sugars but the physics of the resulting product iscomplex. The presence of a fine ice cream microstructure is important toproduce the desired texture and quality of ice cream. Organolepticevaluation of ice cream has shown that small air cells and ice crystalsare associated with increased creaminess and reduced iciness, importantcriteria for good quality ice cream. The use of bulky flavors with freeliquid oil can destabilize the ice cream foam under shear during thefreezing and dosing process, resulting in a coarse air dispersion. Thisoccurs via a mechanism of film spreading of the free oil at theair-water interface resulting in significant gas cell coalescence. Thisdrives further gas cell coarsening via disproportionation resulting in asignificantly increased range of gas cell sizes. In addition, the shearforces exerted during the conveying and dosing of ice cream can furtherdestabilize the foam resulting in a coarser structure and increasedvariation in dosing accuracy.

A typical gas cell size distribution of ice cream ex-freezer is aLog-normal (Galton) distribution; however any destabilization of thefoam affects the distribution of air bubbles in ice cream from thistypical to a more broad distribution. Therefore analysis of the gas celldistribution and degree of deviation from a Log-normal distributiongives an indication of the extent of gas cell coarsening occurring.

We have found that the use of a static mixer will improve thedistribution of the gas cell size by restricting the free oil fromdestabilizing the microstructure of the ice cream. Samples were madeusing both the conventional method illustrated in FIG. 1 and the methodaccording to the invention illustrated in FIGS. 1 and 2 and analyzedwith SEM technology. Images were captured at magnifications of 100-4000times.

SEM images at ×100, ×300, ×1000 and ×4000 were collected to compare thegas cell size and fat at gas cell interfaces. Two spots were imaged foreach ice cream variation.

Processing using both Univat Mixer and Static Mixer (according to theinvention):

At low magnification, no major difference of air cell size was observedamong different peanut butter contents. At high magnification of ×1000and ×4000, more crystal like structures were observed on the gas cellinterfaces with higher peanut butter content.

Process using Univat Mixer but not the Static Mixer (not in accordancewith the invention):

At low magnification, the air cell size range increases with higherpeanut butter content. At high magnification, more crystal likestructures observed on the gas cell interfaces with higher peanut buttercontent.

Comparison:

5% PB ice creams have comparable air cell size between Static and Univatmixer.

The air cell size range becomes wider with increased peanut buttercontent in Univat mixer, while the air cell size remains the same when aStatic mixer is additionally employed in accordance with the invention.

FIG. 3 shows SEM images of ice cream microstructure for a) on the leftan ice cream made using the Static mixer process at 100× magnificationwhere the ice cream contained 12% peanut butter and b) on the right icecream made using the conventional process using a univat without aStatic mixer at 100× magnification where the ice cream contained 12%peanut butter.

FIG. 4 shows SEM images of ice cream microstructure for a) on the leftan ice cream made using the Static mixer process at 100× magnificationwhere the ice cream contained 16% peanut butter and b) on the right icecream made using the conventional process using a univat without aStatic mixer at 100× magnification where the ice cream contained 16%peanut butter.

FIG. 5 shows SEM images of ice cream microstructure for a) on the leftan ice cream made using the Static mixer process at 1000× magnificationwhere the ice cream contained 12% peanut butter and b) on the right icecream made using the conventional process using a univat without aStatic mixer at 1000× magnification where the ice cream contained 12%peanut butter.

FIG. 6 shows SEM images of ice cream microstructure for a) on the leftan ice cream made using the Static mixer process at 4000× magnificationwhere the ice cream contained 12% peanut butter and b) on the right icecream made using the conventional process using a univat without aStatic mixer at 4000× magnification where the ice cream contained 12%peanut butter.

FIG. 7 shows scanning electron microscope images marked to show thediameter of the air bubbles.

Qualitatively, these images help to confirm the advantages of theinvention. At lower magnifications (×100), the presence of very largebubbles (>150 μm) is more common in samples produced by the Univatmethod. In addition, the largest bubbles in the Univat SEMs aresignificantly larger than the largest bubbles in the Static mixer SEMs.Most importantly, the distribution of the bubble size on the Univat inthis experiment is very atypical. There are a large number of very smallbubbles, as well as a few gigantic air pockets. This distribution leadsto poor homogeneity in the frozen ice cream. In addition, thismicrostructure does not hold up well to temperature abuse. At the highermagnification levels (×1000 and ×4000) the free fat is visible as roughcrystalline flakes on the surface of the air bubbles. On the Univatimages, these flakes cover the surface of the air pockets; however,there is a smaller percentage of flakes, not fully dispersed on theStatic Mixer images. The presence of free fat, crystallized into flakes,on the air interface is a prerequisite for air destabilization. Bylimiting the dispersion of the free oil on the air interface, the airphase is kept more stable and the structure of the product ismaintained.

To quantify these results, the size of each bubble needs to be sized.Using an image processing and analysis software called ImageJ, thediameters of each bubble on the ×100 SEM images were marked andmeasured. An example of these marked images can be found in FIG. 7. Thediameter of each bubble was marked, so that the area of that bubble wasaccurately described by that length. A more detailed description of theSEM and image processing technique is provided above.

To compare the samples, the max bubble diameter and the standarddeviation was compared for all of the data. This histogram can be foundin FIG. 8 wherein for each percentage of peanut butter, the bar on theextreme left is the maximum size bubble for the process according to theinvention using the static mixer, the next bar to the right is themaximum size bubble for the conventional process without the staticmixer, the next bar to the right is the standard deviation for theprocess according to the invention using the static mixer and the righthand bar is the standard deviation for the conventional process.

As shown in FIG. 8, the standard deviation and max bubble size of theUnivat samples generally increase as the percentage of PB increases,while the Static mixer data stays relatively similar throughout. Thehistograms do not accurately show the poor distribution of the data dueto the fact that large bubbles take up a large area of the image and aretherefore uncommon.

In order to quantify the distribution, the probability density function(PDF) of a log-normal distribution will be used. A probability densityfunction describes the likelihood for a variable to take a given value.PDFs are dependent on the type of distribution assumed. Therefore, ifthe value of probability density function is compared to the value givenby number of bubbles marked, the relative distribution can be compared.For example, if 1000 air structures are marked, the largest bubbleshould fall near the 99.9 percentile category. This corresponds to a PDFvalue of 0.001 or 0.1 when multiplied to a percentile. The PDF equationfor a log-normal distribution is given below.

${PDF} = {\frac{1}{x*\sigma*\sqrt{2*\pi}}*^{- \frac{{({{lnx} - \mu})}^{2}}{2\sigma^{2}}}}$

FIG. 9 shows a histogram of the PDF values of the largest bubble at eachpercentage evaluated. For each level of peanut butter, the left bar isthe PDF for the process according to the invention, the middle bar isthe PDF for the conventional process lacking the static mixer and theright bar is the log normal. The distribution become less log-normal asthe product goes through more abuse. The hardening process, the shearstress and other factors lead to a more coarse distribution. Thisexplains the low PDF values throughout all of the samples.

This graph shows that at low peanut butter percentages the conventionalprocess using the Univat is successful at creating a typicaldistribution of gas cell size. However, at 12 percent the Univat beginsto fail due to the additional free liquid oil that is spread across thegas cell interface, resulting in the coalescence and coarsening of theair bubbles. The static mixer does not encounter this issue, but has alow value throughout due to the shear stress imparted upon mixing. Atlevels above the 5% tested, the static mixer method has a significantbenefit over the Univat method. To further this point, the fill weightdata presented below shows that this benefit is apparent at 5% withother mix formulas.

Fill weight data that was collected at production plant trialsdemonstrates this effect to a further extent. Data on the weight ofthree different products was collected using the Univat and/or thestatic mixer. The processing used prior to the static mixer was theprocessing typically used in that plant for that product. These threeproducts contain 2.5, 5 and 15 percent by weight peanut butter withinthe ice cream mix or frozen ice cream. The standard percent deviation ofeach product was found using each method and compared. The results arefound in the histogram of FIG. 10 wherein for each level of peanutbutter wt % in the composition, the left bar is for the composition andprocess according to the invention and the right bar is for aconventional product and process.

This data also helps to confirm the invention. It shows that the staticmixer helps to reduce the weight variation in the produced product. Thisweight variation is caused by flow variability in the ice creamproduction process; the flow variability is caused by non-homogeneityand instability of the frozen ice cream foam attributable to addition offree liquid fat present in the peanut butter. In all three products, theuse of the static mixer reduces the standard deviation for the dosingweight. It is important to note that due to scale up, it was notpossible to produce the 15% product without the static mixer on aproduction level, as can be seen in FIG. 10, because the instability ofthe ice cream product was too great.

It should be noted that the examples provided for the weight variationdata are not the same as those in which the gas sizes were measured.Furthermore they are not directly comparable to one another since theformulas and dosing geometries used at each of the % additions were notthe same. However the data for a given % peanut butter additioncomparing the addition method is directly comparable. In general, as thepercentage of peanut butter increases, the static mixer significantlyout performs the Univat with respect to controlling weight variation ondosing.

The invention is also reflected in the fact that the number density ofcrystalline fat particles on the air interface is lower for productsaccording to the invention as compared to the product made using aconventional process. The presence of too many crystalline fat particleson the air interface adversely affects the stability of air bubbles andproduct quality. FIG. 11 shows graphically that the number ofcrystalline fat structures per square micron is substantially higher forthe product made by the conventional process and increases as the wt %of peanut butter increases. The data in FIG. 11 was calculated using theprocedure for quantification of fat crystal structures from SEM imagesset forth above.

Example 1 is repeated using hazelnut butter as the viscous flavorant.

FIG. 13 shows SEM images of ice cream microstructure taken at 1000×magnification for a) on the top, an ice cream made using the Staticmixer process where the ice cream contains 5% hazelnut butter and b) onthe bottom, ice cream made using the conventional process using a univatwithout a Static mixer where the ice cream contains 5% hazelnut butter.

FIG. 14 shows SEM images of ice cream microstructure taken at 1000×magnification for a) on the top, an ice cream made using the Staticmixer process of the invention where the ice cream contains 12% hazelnutbutter and b) on the bottom, ice cream made using the conventionalprocess using a univat without a Static mixer where the ice creamcontains 12% hazelnut butter. At least two, large, spiky, fat structurescan be seen in the right half of the image.

FIG. 15 shows SEM images of ice cream microstructure taken at 1000×magnification for a) on the top, an ice cream made using the Staticmixer process of the invention where the ice cream contains 20% hazelnutbutter and b) on the bottom, ice cream made using the conventionalprocess using a univat without a Static mixer where the ice creamcontains 20% hazelnut butter. A large, well-defined, spiky, fatstructure is visible left of center of the image.

FIG. 12a shows graphically that the number of crystalline fat structuresper square micron is substantially higher for the products made by theconventional process than for the products of the invention; the numberof crystalline fat structures per square micron increases as the wt % ofhazelnut butter and peanut butter increases. FIG. 12b shows graphicallythat the number of crystals/spikes per square micron is substantiallyhigher for the hazelnut butter product made by the conventional processthan for the hazelnut butter product made by the process of theinvention and increases as the wt % of hazelnut butter increases.Results are also shown for peanut butter. The data in FIGS. 12a and 12bwas calculated using the procedure for quantification of fat crystalstructures from SEM images set forth above.

All of this data shows that the static mixer not only removes theallergen from the freezing process, but also improves the quality of theproduct at the microscopic level.

It should be understood of course that the specific forms of theinvention herein illustrated and described are intended to berepresentative only, as certain changes may be made therein withoutdeparting from the clear teaching of the disclosure. Accordingly,reference should be made to the appended claims in determining the fullscope.

1. A process for preparing a frozen confection comprising: a) Mixingingredients; b) Freezing and aerating the mixed ingredients to produce abase frozen confection, c) Feeding a free oil-containing viscousflavoring or other ingredient and the base frozen confection into astatic mixer to produce the frozen confection flavored with a viscous,free oil-containing flavorant/ingredient.
 2. The process of claim 1wherein the proportion of the viscous flavoring/ingredient to the basefrozen confection fed into the static mixer is such that the frozenconfection containing flavorant/ingredient comprises from 6-20 wt % ofviscous flavouring/ingredient.
 3. The process of claim 2 wherein theproportion of the viscous flavoring/ingredient to the frozen confectionfed into the static mixer is such that the frozen confection comprisesfrom 8-15 wt % of viscous flavouring/ingredient.
 4. The process of claim1 wherein the frozen confection flavored with viscous, freeoil-containing flavorant/ingredient is homogeneous to eye and taste. 5.The process according to claim 1 wherein the frozen confection prior tocombining with the flavorant or ingredient in the static mixer has anoverrun of from 20 to 150%.
 6. The process according to claim 5 whereinthe frozen confection prior to combining with the flavorant oringredient in the static mixer has an overrun of from 50 to 120%.
 7. Afrozen aerated confection flavored with a viscous free oil-containingflavorant or ingredient comprising at least 5 wt % viscousflavoring/ingredient and at least 80 wt % of a base frozen confection,said frozen aerated confection having fewer than 0.01 crystallinestructures per square micron of air bubble.
 8. The frozen aeratedconfection according to claim 7 having fewer than 0.009 structures persquare micron of air bubble.
 9. The frozen aerated confection accordingto claim 7 having fewer than 0.0075 structures per square micron of airbubble.
 10. A frozen aerated confection flavored with a viscous freeoil-containing flavorant or ingredient comprising at least 10 wt %viscous flavoring/ingredient and at least 70 wt % of a base frozenconfection, in which the PDF for the largest bubble in the frozenconfection flavored with the viscous flavorant/ingredient is at least0.013.
 11. The frozen confection according to claim 10 wherein the PDFfor the largest bubble is at least 0.015.
 12. The frozen confectionaccording to claim 10 wherein the PDF for the largest bubble is at least0.018.
 13. The frozen confection according to claim 10 wherein thefrozen confection flavored with viscous, free oil-containing flavorantor ingredient is homogeneous to eye and taste.
 14. The frozen confectionflavored with viscous free oil-containing flavorant or ingredientaccording to claim 10 having an overrun of from 20 to 150%.
 15. Thefrozen confection flavored with viscous free oil-containing flavorant oringredient according to claim 10 having at least 12 wt % viscousflavorant or ingredient.
 16. A process for manufacturing a frozenconfection having a viscous, free oil-containing flavorant or ingredientcomprising a) Mixing ingredients; b) Freezing the mixed ingredients toproduce a base frozen confection, c) Feeding a free oil-containingviscous flavoring or ingredient and the base frozen confection into astatic mixer to produce the composite frozen confection wherein thestandard deviation for product weight over 1 hour of production with asample size of at least 4 samples for the frozen confectionincorporating from 5-20 wt % of a viscous flavoring or ingredient havingan oil level of at least 10 wt % is less than 3.5%.
 17. The processaccording to claim 16 wherein the standard deviation for product weightis less than 3%.
 18. The process according to claim 16 wherein theflavored frozen confection is homogeneous to the eye and the taste. 19.The process according to claim 16 wherein the base frozen confection hasan overrun of from 20-150% prior to feeding into the static mixer.